Engine fuel supply, Beta 20hp

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doug748

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The next question in my series of if's and but's about my new engine:
8mm pipe is specified for the fuel system on this engine (BD722). Whilst I do not mind uprating the leak off pipe, I do not fancy draining the fuel tank, and the rest of the palaver with the primary filter, in sorting out 8mm supply:-

Would 6mm do?
Anyone used 6mm with this motor?
Anyone know the max flow rate that 6mm can support, bearing in mind that the maximum fuel consumption is c 4 litres per hour?

Thanks Brian. (PS: yep, I do know the address of Beta Marine)
 
Same engine: 8mm feed; 6mm return; no fuel problems in 1000 hrs running.
But my tank is immediately astern of the engine, so the run is short and almost level.
 
It\'ll be fine...

Your 6mm pipe will be fine. If you want reassurance, here is a link to the spec for a 65hp Cummins, stating minimum size of supply line at 6.4mm.
 
depends on the muck in your tank.

I manage do block up my fuel suction pipe which is 6 mm. with something solid while on passage. When I eventually cleaned it out I found the most amazing lot of solid bits including coarse ginger hair.
Emptying the tank and cleaning it might avoid a lot of unpleasant surprises.
 
Re: depends on the muck in your tank.

I drained the tank last year, a horrible, filthy job. Thats why, with all the other stuff involved in fitting a new motor, I don't want to do it again this winter! Brian
 
[ QUOTE ]
I do not fancy draining the fuel tank, and the rest of the palaver with the primary filter, in sorting out 8mm supply:-

[/ QUOTE ]
Re-read your post and wonder; 'why you would need to drain the tank?' If it correctly designed, the fuel take-off pipe is from the top of the tank, or high up on the side, with a union for the supply-pipe to the engine. You should be able to run a 8mm from there.
Hope this helps.
 
[ QUOTE ]
[ QUOTE ]
I do not fancy draining the fuel tank, and the rest of the palaver with the primary filter, in sorting out 8mm supply:-

[/ QUOTE ]
Re-read your post and wonder; 'why you would need to drain the tank?' If it correctly designed, the fuel take-off pipe is from the top of the tank, or high up on the side, with a union for the supply-pipe to the engine. You should be able to run a 8mm from there.
Hope this helps.

[/ QUOTE ]Duh.. My take off is from the bottom of the tank and is "correctly" designed - no part of the fuel supply line is under negative pressure.
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Re: Coarse ginger hair????

I used 6mm copper pipe on my Beta 25 installed in the spring - no problem at all even running almost full revs for an hour. You should be OK but obviously check your primary filter regularly if you've had problems in the past.
 
[ QUOTE ]
Duh.. My take off is from the bottom of the tank and is "correctly" designed - no part of the fuel supply line is under negative pressure.


[/ QUOTE ]
My source was Ian Nicolson, (Boat Data Book), with sketch of fuel design criteria: with note; ''based on British official recommendations; similar rules apply in other countries''
It shows the fuel feed pipe through the tank top, extending down inside to a sludge trap. -- It also notes ''NO gravity feed from tanks over 9 litres/2 gallons''
I deduce this recommendation is so that fuel cannot be lost into the bilge if/when the fuel line leaks or is broken, and that seems good sense.
 
...badly designed or not, fraid my supply pipe exits at the bottom. The pressure does help the lift pump and tends to make bleeding easier. Nevertheless I have concluded that 6mm is adequate. Thanks for your response everyone.
 
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